The pre-dvh -webkit-fill-available viewport fix freezes Android Chrome's
root at the pre-keyboard height; when interactive-widget=resizes-content
shrinks the viewport, the document stays taller than the screen and the
clipped composer hides behind the keyboard with no way to scroll to it.
dvh-capable browsers now take a dynamic 100dvh instead, and the legacy
fallback keeps serving browsers without dvh.
Bohdan Triapitsyn
ea405eafdc